79 Burbn Project
 

Greeting all,

My boy and I are going to tackle this together, and so here we are because I don't believe any better place exists!

I just picked up this Frankenstein of a rig. The title says c10 sub2500 but it is 4x4. I have not verified everything yet. It is a manual transmission. Pretty sure it's an SM465.(made by Muncie in Saginaw Michigan) I believe np203? It does have locking hubs, front drive shaft and 3/4 ton axles. The previous owner and the vin code tell me 305. I never had a 305 but it looks like a 350 to me. It does have an edlebrock 4bl. It runs and drives OK, but the gearing is super low. My top speed without pushing or knowing rpm is about 45mph. Owner also says the axle gears are 5? something. The tranny rumbles while driving in gear and makes like crackling sound shifting in and out of gears. Clutch pedal and stick are also sloppy as all git out too. All that just to give you an idea where I'm at... kinda. Let's not talk about the inside yet. I'll save that for more fun later...

This is my question. Do I rebuild the SM465 or convert to something else? Like maybe an NV4500 just because of the 5th gear/overdrive.

Since it runs and drive OK, I think this is where I need to start.

Thanks a million,

Re: 79 Burbn Project
 

Looks like a great start.

I have a few trucks with the SM465 and while they give you a true old truck feel when driving, I get tired driving them after a couple of days because the creeper gear is too low for take off and 2nd gear is always a little too high. You can get the hang of it after a while but still not my favorite driving manual transmission for sure.

Just my opinion, if the transmission is already sloppy I wouldn't put money into it but would instead swap to an automatic with its mating transfer case, radiator, and driveshafts out of a donor truck. If you really want to stick with the SM465 then I'd look for a used one in working condition rather than putting money into rebuilding the one you have. They're pretty bomb proof so you should be able to find a good one laying around in someone's parts pile.

Your suburban should have 4.10 or 4.56 at the lowest axle ratios.

Re: 79 Burbn Project
 

Thanks for the input Willowrun,

I think you make a good point about getting a used replacement. At least it would make it more drive-able for the time being.